(337c) 3D Printed MOF Monoliths for Sub-Ambient Direct Air CO2 Capture

My research interests focus on solving challenging chemical separation problems including but not limited to CO2 capture, hydrocarbon separation, and water purification. In addition, I am also interested in harnessing the fundamentals of material synthesis, material characterizations, and process integration to develop products or processes for better environmental sustainability.

Poster abstract:

Current carbon drawdown scenarios require deployment of direct CO₂ capture technologies to reduce atmospheric CO₂ concentration. Supported amine materials based on zeolite, silica, and metal-organic frameworks (MOFs) have been demonstrated as promising adsorbents for direct CO₂ capture, but the shaping and structuring of these materials into sorbent modules for practical processes have been inadequately investigated compared to the extensive research on material development.

Supported amine materials based on zeolites, silica, and metal-organic frameworks (MOFs) have been demonstrated as promising adsorbents for direct air CO₂ capture (DAC), but the shaping and structuring of these materials into sorbent modules for practical processes have been inadequately investigated compared to the extensive research on material development. Furthermore, there have been sparse studies reporting the DAC performance of sorbent contactors under sub-ambient conditions (temperature below 293 K). In this work, we demonstrate the successful fabrication of adsorbent monoliths composed of cellulose acetate (CA) and adsorbent particles by a 3D printing technique, solution based additive manufacturing (SBAM). These monoliths feature interpenetrated macroporous polymeric frameworks where sorbent powder are evenly distributed, suggesting the versatility of SBAM in fabricating monoliths containing sorbents with different particle sizes and density. Branched polyethylenimine (PEI) is successfully loaded into the CA/MIL-101(Cr) monoliths to impart CO₂ uptakes of 1.1 mmol g(monolith)^−1 at 253 K. Kinetic analysis shows that the CO₂ sorption kinetics of PEI-loaded MIL-101(Cr) sorbents is not compromised in the monoliths compared to the powder sorbents. Importantly, these monoliths exhibit promising working capacities (0.95 mmol g^−1) over 14 temperature swing cycles with a moderate activation temperature at 333 K. Dynamic breakthrough experiments at 298 K under dry conditions reveal a CO₂ uptake capacity of 0.60 mmol g(monolith)^−1, which further increases to 1.05 and 1.43 mmol g(monolith)^−1 at 253 K under dry and humid (70% relative humidity) conditions, respectively. Our work showcases the successful implementation of SBAM in making DAC sorbent monoliths with robust CO₂ capture performance over a wide range of operation temperatures, suggesting the great potentials of SBAM in preparing sorbent contactors in various form factors for other important chemical separations.